Hi , I'm having the same trouble as you had with emissions PO455. This has been going on for 3 years now and no one can find the problem. Do you know of a way I can reset the light. The emissions places are different one place failed me another passed me. I'm so confused. The shop I took it to checked it
and said there was no leak. Emissions says it is. I have a 2002 jeep Gr. Cherokee.
Help
JoAnn
Originally Posted by Skatchkins
Email Question:
Reset the light as in make it go away? Un hook the bat for a few hours. This will reset the comp. Or take it back to the shop and ask them to clear it.
Touch the cow. Do
it NOW!
Pulled from the AllDataPro info:
SYMPTOM P0455-EVAP LEAK MONITOR LARGE LEAK DETECTED
TEST NOTE All symptoms listed above are diagnosed using the same tests. The title for the tests will be P0442-EVAP LEAK MONITOR MEDIUM (0.040) LEAK DETECTED.
WHEN MONITORED
Immediately after a cold start, with battery/ambient temperature between 40 �F and 90 �F and coolant temperature within 10 �F of battery/ambient.
SET CONDITION If there is a leak larger than 0.080" in the evaporative system.
POSSIBLE CAUSES
* Leak at Gas Cap * Vehicle History and Service Bulletin Investigation * Visual and Physical Inspection * Verify Evaporative Emission Leak * EVAP Purge Solenoid Operation * Intermittent LDP Monitor Failure *
Evaporative Emission Leak Detection * Gas Cap * LDP Component Leak
for mine I reset the PCM right before I went in for the test. This made the light stay off for about 8 start up/ shutdowns
Heres the info on how to reset the PCM
http://higherground4x4.com/forums/showthread.php?t=498
Zombie Caving Siblings are like sausages. It�s better not to see them being made.
Have you changed the gas cap?
Can you read those or did it convert them to "super tiny"?
Zombie Caving Siblings are like sausages. It�s better not to see them being made.
I think this made them readable.
Zombie Caving Siblings are like sausages. It�s better not to see them being made.
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One of the most common trouble codes with the Jeep Grand Cherokee is the P0455 code. This trouble code references a number that is given to you when you plug your Grand Cherokee into a OBD2 scanner, and has to do with the emissions system. P0455 Indicates that there is a large leak in the
evaporative emission control system (EVAP). It often appears with, or is related other codes, such as P0420, P0430, P0441, and very often P0440.
P0455: EVAP System → Leak Detected (Large)
P0455 is normally not an immediate threat to the drive-ability of your
Grand Cherokee. Certainly anytime the service engine soon light is on, it’s good to deal with it as soon as possible though.
Jeep Grand Cherokee P0455 Definition
P0455 is a universal OBDII trouble code. This means that regardless of which make or model of vehicle, the code will mean the same thing (Grand Cherokee or not). The code technically stands for:
System Gross Leak Evaporative Emission System
The EVAP system captures all fuel vapor from the fuel tank and sends
them to the engines intake in order to be ignited in the normal combustion process. When there is a large leak in the Jeep Grand Cherokee’s EVAP system, it will throw the P0455 OBDII Code.
Jeep Grand Cherokee P0455 OBDII Code Symptoms
The service engine soon light is often the only sign that the P0455 code has been triggered
P0455 code will typically not be accompanied by any noticeable symptoms other than the smell of gas and the service engine soon light. You may notice the slightest dip in fuel economy as well.
You should particularly notice the smell of fuel around the fuel tank area or fuel filler tube.
The EVAP system deals directly with fuel vapors. If these vapors are leaking from the system, you’ll often smell them faintly while operating the vehicle.
Grand
Cherokee P0455 Trouble Code Causes
There are many things that can cause the P0455 trouble code to trigger in your Jeep Grand Cherokee. Here are the most common problems that will throw the code:
Evap System Hose– The hose that carries the fuel vapor from the fuel tank to the intake manifold can begin to leak. This will cause the P0455 code. Look for either a tear or hole in it. This is one of the most common issues that causes the code
Vapor
Canister Purge Valve– One of the most common causes of the P0455 code is the vapor canister purge valve. It’s really easy to replace. There are a few clips that you need to find and remove.
Faulty Charcoal Canister– The charcoal canister is often the cause of P0455.
Fuel Tank Sending Unit– It is possible for the gasket that attaches the fuel sending unit to the gas tank to go bad. This can reduce tank pressure and throw the code.
Fuel Cap– A bad fuel cap can cause the code to be thrown for sure. Often, you’ll get a message informing you that the fuel cap is off even when it is on. If you are getting that message, plus a P0455, it may save you a ton of time and money to replace the fuel cap and see if it goes away.
Fuel Filler Neck– There is often a gasket where the fuel filler neck connects with the gas tank. This gasket can dry out, especially with vehicles that spend their
time in dry climates. When it dries out, the fuel tank can’t hold pressure anymore.
P0455 Diagnosis- Jeep Grand Cherokee
A mechanic has a wide range of instruments at his disposal to diagnose what would be causing the P0455 in your Jeep Grand Cherokee. Here are the most common things that are done to diagnose the code:
The mechanic will typically check to see if there are any other trouble codes. The more trouble codes there are, the easier it can be to diagnose a
problem. That’s because when they appear together in certain combinations, there will often only be only a few conditions that will throw any combination of codes at one time.
After ascertaining what trouble codes appear with the P0455, the mechanic will typically inspect the EVAP system. This includes the purge valve, line, and canister.
The mechanic will inspect the gas cap to make sure that it can handle pressure. If you are getting a warning that your gas cap is off,
even when it’s on, replacing it will more than likely clear this code.
The fuel tank pressure will be checked and monitored.
After for the checks and fixes listed above, the mechanic will perform two tests:
A smoke test, and they’ll use a scan tool to confirm that the EVAP solenoids and valves are operating properly.
Here’s a pretty good video on diagnosing these leaks from Scotty Kilmer, if you are interested:
While the trouble code may state that there is a “large leak” in the EVAP system of your Jeep Grand Cherokee, the actual leak will most likely still look rather small. The “large” really is referring to how much pressure is being lost.
Most Common P0455 Fixes
Here are the most common Grand Cherokee P0455 fixes:
Gas
cap replacement
EVAP line replacement
Replace charcoal canister
Replace the fuel tank
Of all the items listed above, it would be wise to start with the gas cap and work your way to the fuel tank, since the gas cap is far and away the easiest and least expensive items to replace on here.
Here’s a great video on how to test your gas cap.
Good luck figuring out what is causing
your Jeep Grand Cherokee to throw the P0455 code. We hope this helps. If there is anything that you feel like you could add, please feel free to leave a comment below.
Is P0455 a Serious Concern?
While P0455 is not going to cause the Grand Cherokee’s engine to stop running, it should not be treated lightly. You could have a fuel leak. Pay extra attention to your tank level and make sure you are not leaking fuel. We recommend taking it in and/or dealing with it right away.
How do I fix code P0455?
Replacing the cap can most likely solve the problem. The Engine Check light will turn off and the code will erase after a few drive cycles. If this does not fix the issue, the EVAP hoses from the gas tank to the canister and from the canister to the air intake must be examined.
What is code P0455 on a Jeep Grand Cherokee?
The P0455 Jeep code occurs when the PCM detects a large EVAP leak. Symptoms include an illuminated CEL, subpar engine performance, stalling, and excessive exhaust smoke (among others). A malfunctioning gas cap or a defective emissions control system component can cause the fault code.
What is code P0455 EVAP large leak?
P0455 is a fairly straight forward OBD-II trouble code, in that it tells us that the engine computer has detected a large leak in the engine Evaporative Emissions Control (EVAP) system. The EVAP system prevents fuel vapors from escaping into the atmosphere.
What would cause a large EVAP leak?
A common cause is a missing or loose gas cap. This easy-to-fix solution could be all you need to restore your EVAP system. However, minor tears, or rotten spots in your EVAP hose could also be the culprit. Your filter canister may also be cracked.
